Class 1 Wiring, 0-10 Volts

infinity

Moderator
Staff member
I saw this on a job where the 0-10 volt wiring was brought out of the junction box and spliced. Doesn't class 1 wiring need to be within the box? I was told that some inspector didn't want those splices within the box. My argument was that on the other end in the fixture they're all spliced in the same junction box so what did this accomplish?

don_resqcapt19

Moderator
Staff member
Once you classify the circuit from Class 2 to Class 1, it must be installed per the requirements in Chapter 3 and the splices would have to be in a box.

hbiss

EC, Westchester, New York NEC: 2014
Those blue cables from the bottom of the box on the left are not Class 1, they are CL2 cables run with Class 1 conductors from the "luminary" MC. They are spliced with the reds and blacks from the relays outside the box on the right.

Dunno.

I suppose when you have one set in a fixture it's no big deal but that many all in one place- better to have them separate.

-Hal

infinity

Moderator
Staff member
Once you classify the circuit from Class 2 to Class 1, it must be installed per the requirements in Chapter 3 and the splices would have to be in a box.
That's was my thought was as well. I believe I saw something in the literature for those relays that states that they are Class 1. In fact if you need 0-10 volt control with Class 2 they route the Class 2 wires out through a separate hole so they do not end up in the box with the power conductors.

hbiss

EC, Westchester, New York NEC: 2014
... I believe I saw something in the literature for those relays that states that they are Class 1. In fact if you need 0-10 volt control with Class 2 they route the Class 2 wires out through a separate hole so they do not end up in the box with the power conductors.

The LOAD does not determine what the class is, only the power source. Not sure what the literature is saying by stating those relays are Class1. The contacts and line voltage conductors are, of course.

In the situation above, you need to maintain 1/4" separation between the 0-10V CONDUCTORS, not the cables and the line voltage conductors when in the same enclosure or box. So the cables could have been run into the box on the right and the stripped conductors spliced there but maintaining the required spacing would be impossible.

-Hal

Flicker Index

Senior Member
Can't come in and out like that. Once reclassified as Class 1, everything has to be wired using Class 1 methods.

hbiss

EC, Westchester, New York NEC: 2014
Can't come in and out like that. Once reclassified as Class 1, everything has to be wired using Class 1 methods.

They are NOT reclassified as class 1! You are looking at CL2 cables. And actually there is no such thing as reclassifying anymore.

-Hal

GoldDigger

Moderator
Staff member
They are NOT reclassified as class 1! You are looking at CL2 cables. And actually there is no such thing as reclassifying anymore.

-Hal
Would you expand on that?

hbiss

EC, Westchester, New York NEC: 2014
Would you expand on that?

Last I looked to answer this same question it looked like it was dropped from the '17.

-Hal

GoldDigger

Moderator
Staff member
Last I looked to answer this same question it looked like it was dropped from the '17.

-Hal
What about 725.130 in '17 and '20???

Last edited:

hbiss

EC, Westchester, New York NEC: 2014
Hmmm. Still there even in the '20. Don't remember what I was thinking of I guess.

-Hal

GoldDigger

Moderator
Staff member
Happens to me sometimes too.

romex jockey

Senior Member
this?????>>>

Informational Note: Class 2 and Class 3 circuits reclassified and
installed as Class 1 circuits are no longer Class 2 or Class 3
circuits, regardless of the continued connection to a Class 2 or
Class 3 power source.

~RJ~

GoldDigger

Moderator
Staff member
this?????>>>

Informational Note: Class 2 and Class 3 circuits reclassified and
installed as Class 1 circuits are no longer Class 2 or Class 3
circuits, regardless of the continued connection to a Class 2 or
Class 3 power source.

~RJ~
Very oddly worded. I think that the intent is not that you cannot use Class 1 wiring to interconnect a Class 2 supply but that:
1. The intended load must be rated for Class 1 (even if most common use is with a Class 2 supply) and
2. Once you have reclassified, the entire length of the circuit must use a Class 1 method instead of mixing Class 1 where needed to run with power and Class 2 in other areas.
Both seem reasonable to me.